One would have to go through leaps and bounds of ignoring parts of
the specification and overzealously interpreting other parts to come
to the conclusion that rfc2396bis specifies that mailto URIs must
(or must not) percent-encode a "@" in path. There is simply no basis
for your claims. That decision is specifically left to the mailto
specification to define, which it will when that spec is revised.
In the mean time, the implementations do not need to be changed,
there is no concern for interoperability, and the URI specification
is already at Full Standard status. I suggest you find some other
outlet for your energy, such as converting the mailto draft to XML
and fixing the bits you want fixed so that it can be revised.
....Roy